Telephonic receiving instrument



(No Model.)

W. B. HALE,

I TELEPHONIG RECEIVING INSTRUMENT. No. 254,642. Patented Mar. 7,1882.

-which core has its UNITED STATES PATENT OFF-ICE.

WILLIAM B. IEIALE, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOIt TO THE UNITED STATES TELEPHONE MANUFACTURING COMPANY, OF

new YORK, n. Y.

TELEPHONIC RECEIVING-INSTRUM ENT.

S2ECIFICATION forming part of Letters Patent No. 254,642, dated March'7, 1882.

Application filed July 26, 1881. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM B. HALE, a citizen of the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Telephonic Receiving-Instruments; and I do herebydeclare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had 'to the accompanyin gdrawin gs,

and to the letters or figures of reference marked thereon, which form a part of this specifics tion.

This invention relates to a telephonic receivlug-instrument in which the vibrations of a diaphragm are caused by the action thereupon of an iron or steel core, which lengthens and shortens under the influence of electric cur rents traversing a surrounding coil of wire.

A telephonic receiver of this class has heretofore been invented in directly upon the center of a is confined at its periphery. The object of my invention is to give a more effective vibration to the diaphragm, and to concentrate the air-vibrations produced there by. This I accomplish by confining the'diaphragm at a single central point only and ex erting upon its outer margin the mechanical force which causes it to vibrate, this margin being left free to move in response to the action of the core. it

In the accompanying drawings, Figure 1 is a central longitudinal section of a telephonic receiving-instrument constructed according to my invention, and Fig. 2' is a similar section of a modification thereof.

Referring to Fig. 1, the letter A indicates a diaphragm of any suitablcmaterial, either magnetic or non-magneticsay, for instance, thin sheet metal, mica, hard rubber, or wood. The margin of this diaphragm rests freely against the edge of acup, B, which .has at its center an aperture, in which is screwed one end-of a hollow or tubular core, 0, of either iron or steel, other end abutted against which 'isQbored centrally. the diaphragm is secured diaphragm which a block of lead, D, To the center of which the core acts.

not move rearwardly one end of. a non-magnetic rod, E, which extends through the tubular core 0, the lead block D, and a'washer, F, and hasits other end screw-threaded to. receivea thumb-nut, G, by which its strain upon the diaphragm may be regulated.

The letter C indicates a coil of wire surrounding a portion of the hollow core 0, and having its terminals counected'respectively with the binding-posts h, arranged at the end of the case I, in which the described parts are inclosed, said case having a front ear-piece, I, with a central aperture, 4, through which the air-vibrations pass outward from the diaphragm A. I 7

It is known that when an electric current traverses a coil of wire which includes an iron or steel core the core expands,,and resumes its normal position as the circuit is made or broken or the current is varied in .strength. When, therefore, an electrical current is caused to traverse the coil 0, the core 0 elongates, driving the edge of the cup B against the margin of the diaphragmA,.giviug said diaphragm an outward half-vibration all around the central point which is confined by the rod E; and if the current ceases to How, or its strength is decreased, the core 0 contracts wholly, or in proportion to the decrease in the strength of the current, drawing backward the cup B, allowing the diaphragm to resume or approac its normal position. When an electrical current is transmitted over the coil (3' by means of any suitable telephonic transmitting apparatus the lengthening and shortening of the core G, and consequently the vibrations of the diaphragm A, correspond to the variations of the current, the air vibrations or undulations emanating from the diaphragm producing sounds similar to those which cause the action. of the transmitting apparatus.

It will be understood that when the current ceases in the coil or its strength becomes less, the core does not shorten to less than its normal length, but simply resumes or approaches that length, and therefore the diaphragm does on its return vibration beyond its normal position. It therefore has no tendency toward an on twardly-convex form but by the action of the edge of the cup upon its margin it is concaved rather toward a central line, this action tending to cause a com vergence of the air-vibrations, resulting in the production of louder sounds than is the case where the center of the diaphragm is projected outward, giving the diaphragm a convexity tending to disperse the airvibrations or undulations.

The ahutmentD, I make ot'lead, because that metal is magnetically inert and non-vibratory, so that it is a perfect stop for the core 0, the efi'ective lengthening of which therefore takes place in the direction of the diaphragm.

In the modification illustrated in Fig. 3, the diaphragm is formed with an especial view. to the condensing of the air vibrations or undulations toward a focus.

The letter A designates a hollow conical diaphragm having a flange, a, against which rests the base edge of a surrounding larger hollow cone, B, having an opening in its' apex in line with an opening in the apex of the center of the diaphragm A.

The letter C denotes the hollow core ot an electro-magnet, of which (3 is the coil. The core 0 has one end bearing against the end of the cone B, and the other end abetted against the end of a centrally-bored cylinder, D, of lead, and preferably arranged in a socket or countersink in said'cylinder.

A non-magnetic tension-rod, E, (preferablyof brass or other metal of considerable tensile strength, and not appreciably or but little af-' .fected by electric curren ts,) has a head, 6, fitted snn'gly in the tip of the diaphragm A, and ex tends through the same and through the opening of the cone B, the hollow core and the bore of the lead cylinder D, having a screwdiaphragm to vibrate and threaded portion extending beyond said cylinder and through the end of the case 1 outside of which it is provided with a thumb-nut, G", and a suitable washer. The thumb-nut being screwed up to press its washer firmly against the case, the flange a is drawn against the edge of the cone B, thetip of which is pressed against the adjacent end of the core 0 the other end of which is drawn against the lead cylinder. The force with which the parts are thus pressed togetheris regulated by the thum bnut, and should be such (as also in the form shown in Fig. 1) that none of the eflect of the elongation of the core will be lost. When, now, electric currents of proper character are passed over the coil 0 the core 0 will be elongated and contracted in correspondence with said currents, driving the edge of the coneB against thejflange a of thediaphra'gm, causing said generate from its surface air vibrations or undulations, which converge toward a sound-producing etfect being more intensified common focus, their united as the lines of vibration approach their ultimate point of convergence.

What I claim is 1. In a telephonic receiving-instrument, the combination, with a diaphragm which is fixed at its center, but capable of vibrating at its perimeter and betweeni ts perimeter and center, of an electromagnet having its core fixed at one end, and mechanical means for transmitting motion from the other end of said core to the margin of the diaphragm when said core is caused to expand by the influence of electric currents, substantially as described.

2. In a telephonic receiving-instrument, the combination, with a vibratory ing its center confined,-of van electro-magnet having its core provided with an extension impinging against the margin of said diaphragm and arranged to cause the same to vibrate in influence of electric currents traversing the coil of the magnet, substantially as described.

3. In a telephonic receiving-instrument, the

diaphragm havresponse to the'action-ofthe core under the.

combination, with the vibratory diaphragm, of

an electro-magnet having'a t'nbnlarcore provided with-an extension impinging against the margin ofsaid diaphragm, a rod having one end secured to the center of said diaphragm and passing through the tubular core of the magnet, its other end beiugfixed, able stop for the end of the core that next thediaphragm'.

4. The combination, with a suitably-supported concave diaphragm, of the tubular-core of an electro-mag-net arranged to bearagainst said diaphragm, a rod extending from the apex of said diaphragm through the core of the magnet, and arranged ,to hold the center of the diaphragm in a fixed position with relation to the core, substantially asdescribed.

5. The combination, with the vibratory diaphragm,'ot' an electro-magn'ct having a tubular core, one end of which is provided with an extension bearing against the margin of said diaphragm, and the other end resting against a magnetically inert support, a rod secured to opposite to and a suittoo the center ofsaid diaphragm and extending through the tubular core of the magnet, and arranged to hold the center of the diaphragm in a fixed position with relation to the core, substantially asdes'cribed.

In testimony whereof Iaflix my signaturein presence of two witnesses.

WiLmAM B. HALE.

Witnesses: 7 WM. H. BATES, CHARLES E. BUELL.

-IIO 

